Benefit Plans - The Company's Pension Plan Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Defined Benefit Plan Disclosure
Total pension plan assets	$ 100,478	$ 78,502
Insurance contracts and other
Defined Benefit Plan Disclosure
Total pension plan assets	2,565	756
Cash and cash equivalents
Defined Benefit Plan Disclosure
Total pension plan assets	4,522	565
Equity securities
Defined Benefit Plan Disclosure
Total pension plan assets	8,623	20,935
Fixed income
Defined Benefit Plan Disclosure
Total pension plan assets	31,675	56,246
Bulk annuity contract
Defined Benefit Plan Disclosure
Total pension plan assets	53,093
Level 1
Defined Benefit Plan Disclosure
Total pension plan assets	8,537	6,718
Level 1 | Insurance contracts and other
Defined Benefit Plan Disclosure
Total pension plan assets	0	0
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure
Total pension plan assets	654	387
Level 1 | Equity securities
Defined Benefit Plan Disclosure
Total pension plan assets	1,719	1,796
Level 1 | Fixed income
Defined Benefit Plan Disclosure
Total pension plan assets	6,164	4,535
Level 1 | Bulk annuity contract
Defined Benefit Plan Disclosure
Total pension plan assets	0
Level 2
Defined Benefit Plan Disclosure
Total pension plan assets	32,085	0
Level 2 | Insurance contracts and other
Defined Benefit Plan Disclosure
Total pension plan assets	1,880	0
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure
Total pension plan assets	3,868	0
Level 2 | Equity securities
Defined Benefit Plan Disclosure
Total pension plan assets	6,904	0
Level 2 | Fixed income
Defined Benefit Plan Disclosure
Total pension plan assets	19,433	0
Level 2 | Bulk annuity contract
Defined Benefit Plan Disclosure
Total pension plan assets	0
Level 3
Defined Benefit Plan Disclosure
Total pension plan assets	53,778	609
Level 3 | Insurance contracts and other
Defined Benefit Plan Disclosure
Total pension plan assets	685	609
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure
Total pension plan assets	0	0
Level 3 | Equity securities
Defined Benefit Plan Disclosure
Total pension plan assets	0	0
Level 3 | Fixed income
Defined Benefit Plan Disclosure
Total pension plan assets	0	0
Level 3 | Bulk annuity contract
Defined Benefit Plan Disclosure
Total pension plan assets	53,093
NAV
Defined Benefit Plan Disclosure
Total pension plan assets	6,078	71,175
NAV | Insurance contracts and other
Defined Benefit Plan Disclosure
Total pension plan assets	0	147
NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure
Total pension plan assets	0	178
NAV | Equity securities
Defined Benefit Plan Disclosure
Total pension plan assets	0	19,139
NAV | Fixed income
Defined Benefit Plan Disclosure
Total pension plan assets	6,078	$ 51,711
NAV | Bulk annuity contract
Defined Benefit Plan Disclosure
Total pension plan assets	$ 0